These are two very different products. Reduct XT will help control cortisol, but Sup3r-11 also contains cortisol reducing properties. If you've never used Sup3r-11 I wouldn't recommend stacking two different cortisol products. You want to control cortisol, not eliminate it. If you were considering using Reduce XT, my recommendation would be run it after your current stack, or even 4-6 weeks after to give your body a break from hormonal products.
Slinmax is geared more toward carbohydrate intake and nutrition. Depending on your carb intake, Slinmax would be a great addition to a cutting diet. When I diet, I rely on carb cycling, and Slinmax is a life saver. I feel that I'm able to eat more carbs and digest them better without holding excess water and getting bloated. Its also a great product to have on hand if you plan to incorporate cheat days/meals in your cut